1. Field of the Invention
The present invention relates to a method of manufacturing an electrophotographic photosensitive member which comprises forming a functional film.
2. Related Background Art
Glass, heat-resistant synthetic resin, stainless steel, and aluminum are proposed as a substrate for forming a deposited film of an electrophotographic photosensitive member. Practically, however, a metal is frequently used as the substrate in order to withstand such photographic processes as charging, exposure, development, transfer and cleaning and always keep a high positional accuracy without deteriorating the picture quality. Particularly, aluminum is one of the optimum materials as the substrate of an electrophotographic photosensitive member because it has a high workability and a low cost and is lightweight.
The technologies concerned with the material of the substrate of an electrophotographic photosensitive member are disclosed in Japanese Patent Application Laid-Open Nos. 59-193463 and 60-262936. Japanese Patent Application Laid-Open No. 59-193463 discloses the technology for obtaining an amorphous-silicon electrophotographic photosensitive member showing a high picture quality by using an aluminum alloy having an Fe content of 2,000 ppm or less as a support. Moreover, it discloses the procedures of cutting a cylindrical substrate with a lathe and mirror-finishing it and thereafter forming amorphous silicon by glow discharge. Japanese Patent Application Laid-Open No. 60-262936 discloses an extruded aluminum alloy superior in the vapor deposition characteristic of amorphous silicon containing 3.0 to 6.0 wt % of Mg, and as controlled impurities, Mn amount not more than 0.3 wt %, Cr amount less than 0.01 wt %, Fe amount not more than 0.15 wt %, Si amount not more than 0.12 wt % and the remainder of Al.
These materials undergo a substrate surface treatment in accordance with applications of an electrophotographic photosensitive member and a light receiving layer is formed on the substrate surface. The technology concerned with the substrate surface treatment is disclosed in Japanese Patent Application Laid-Open Nos. 61-231561 and 62-95545. Japanese Patent Application Laid-Open No. 61-231561 discloses the method of naturally dropping a rigid complete sphere to form irregularity on the surface of a metallic support by the trace dent of the sphere. Japanese Patent Application Laid-Open No. 62-95545 discloses the method of forming irregularity by a solution obtained by mixing polybutene and triethane (trichloroethane: C.sub.2 H.sub.3 Cl.sub.3). It is described that these technologies are effective for generation of an interference fringe on a picture.
Moreover, concerning a method of working a substrate before surface roughening, Japanese Patent Application Laid-Open No. 61-171798 discloses the technology for obtaining an electrophotographic photosensitive member such as of high-quality amorphous silicon by cutting a substrate with a cutting lubricant containing a specific component. Furthermore, it is disclosed cleaning the substrate with triethane (trichloroethane: C.sub.2 H.sub.3 Cl.sub.3) after cutting. However, it does not disclose cleaning with water containing a specific inhibitor at all.
Furthermore, as a corrosion-preventive technology for the water cleaning step when using an aluminum alloy as a substrate, Japanese Patent Application Laid-Open No. 6-273955 proposes the technology for cleaning a substrate with water containing carbon dioxide. However, cleaning with water containing a specific inhibitor is not described at all. Furthermore, it does not disclose at all defining a film thickness and a composition ratio in a certain range by water containing a specific inhibitor.
Furthermore, Japanese Patent Application Laid-Open Nos. 63-311261 and 1-156758 and Japanese Patent Publication No. 7-341223 respectively disclose the technology for forming an oxide film on an Al substrate. However, they do not disclose forming a film by cleaning with water containing an inhibitor as a specific component.
Japanese Patent Application Laid-Open No. 61-273551 discloses the technologies for alkaline cleaning, trichloroethylene cleaning, and ultraviolet irradiation cleaning by using a mercury lamp as pretreatment of a substrate when manufacturing an electrophotographic photosensitive member by vapor-depositing Se or the like on an aluminum substrate. Moreover, it discloses performing liquid degreasing cleaning, steam degreasing cleaning, and pure water cleaning for removing fat attached to the surface of a cylindrical aluminum substrate as the pretreatment of ultraviolet irradiation cleaning. Furthermore, Japanese Patent Application Laid-Open No. 63-264764 discloses the technology for roughening the surface of a substrate with a water jet. However, it does not disclose cleaning with water containing a specific inhibitor at all.
Japanese Patent Application Laid-Open No. 1-130159 discloses the technology for cleaning an electrophotographic photosensitive member support by water jet. It discloses amorphous silicon in addition to Se and organic photoconductor as examples of photosensitive members. However, it does not disclose problems peculiar to plasma CVD at all.
As the technology for element members used for electrophotographic photosensitive members, various materials are proposed including selenium, cadmium sulfide, zinc oxide, amorphous silicon, and organic compounds such as phthalocyanine. Particularly, a non-single-crystal deposited film containing silicon atoms as a main component which is represented by amorphous silicon, for example, an amorphous deposited film such as of amorphous silicon compensated by hydrogen and/or halogen (e.g., fluorine or chlorine) is proposed as a high-performance, high-durability and pollution-free photosensitive member and some types of amorphous deposited films are practically used. Japanese Patent Application Laid-Open No. 54-86341 discloses the technology for an electrophotographic photosensitive member in which a photoconductive layer is mainly formed of amorphous silicon.
Many methods for forming a non-single-crystal deposited film containing silicon atoms as a main component have been known so far, including the sputtering method, the method of decomposing a source gas by heat (thermal CVD method), the method of decomposing a source gas by light (optical CVD method), and the method of decomposing a source gas by plasma (plasma CVD method).
The plasma CVD method, that is, the method of forming a thin deposited film on a substrate by decomposing a source gas by DC, high-frequency, or microwave glow discharge is most suitable for a method of forming an amorphous-silicon deposited film for electrophotography and therefore, it is frequently practically used at present. Particularly, the plasma CVD method using microwave glow discharge decomposition, that is, the microwave plasma CVD method has been recently industrially noticed as a deposited-film forming method.
The microwave plasma CVD method has advantages of a high deposition rate and a high source-gas utilization efficiency in comparison with other methods. One of the microwave plasma CVD technologies making the most use of these advantages is disclosed in U.S. Pat. No. 4,504,518. The technology described in this patent makes it possible to obtain a high-quality deposited film at a high deposition rate and a low pressure of 0.1 Torr or less by the microwave plasma CVD method.
Moreover, the technology for improving the source-gas utilization efficiency by the microwave plasma CVD method is disclosed in Japanese Patent Application Laid-Open No. 60-186849. In short, the technology disclosed in it greatly improves the source-gas utilization efficiency by arranging a substrate so as to surround a microwave-energy introduction means and forming an internal chamber (that is, discharge space).
Furthermore, Japanese Patent Application Laid-Open No. 61-283116 discloses the improved microwave technology for fabricating a semiconductor member. That is, it discloses the technology for improving characteristics of a deposited film by providing an electrode (bias electrode) for controlling a plasma potential in a discharge space and depositing a film while applying a desired voltage (bias voltage) to the bias electrode and controlling the ion impact to the deposited film.
When using an aluminum-alloy cylinder as a substrate, the conventional method of manufacturing an electrophotographic photosensitive member in accordance with these prior technologies is specifically executed as shown below.
A substrate for the photosensitive member is worked so as to have a predetermined flatness by the diamond cutting using a lathe or milling machine according to necessity and then, cleaned with triethane. In some cases, the substrate is finished so as to have a predetermined or optional irregular surface in order to prevent interference.
Moreover, to form an irregular shape, a spherical trace dent is formed as shown below by using the apparatus shown in FIG. 8. As shown in FIG. 8, for example, a spherical trace dent 4 is formed by naturally dropping a rigid complete sphere 3 from a position higher by h than a surface 2 to make it collide with the surface 2. Moreover, it is possible to form a dent at a predetermined density in accordance with the hardnesses of the rigid complete sphere and metal surface as the occasion demands.
Thereafter, a deposited film mainly made of amorphous silicon serving as a photoconductive-member deposited film is formed on a substrate by the glow-discharge decomposition method. Then, an electrophotographic photosensitive member is manufactured by using the deposited film thus obtained.
However, abnormally grown portions are formed in a deposited film in the case of an electrophotographic photosensitive member manufactured in accordance with the prior technology and the portions become portions having no surface charge of a very small area. These phenomena particularly appear on an electrophotographic photosensitive member comprising a deposited film formed by the plasma CVD method like the case of amorphous silicon. However, the portions having no surface potential can be minimized by optimizing the surface-treatment, cleaning, and depositing conditions and no problem has practically occurred so far because of the degree of the resolving ability of development or lower.
Recently, however, (1) the resolution ability of development has been improved because it has been requested to make the picture quality of an electrophotographic device higher, and (2) as the operation speed of a copying machine has been accelerated and the electric charge condition has been severer, a portion having a surface with no potential has substantially greatly influenced peripheral potentials.
These very small portions having no electric charge have been pointed out as image defects though they have not been a problem in the prior art.
Moreover, these image defects have not practically been a large problem so far because a copy has been mainly used for a manuscript having only characters (so-called line copy).
However, as the picture quality of a copying machine has been improved in recent years, a manuscript including half tone such as a photograph has been frequently copied. Particularly, in the case of a color-copying machine having been recently spread, because these defects visually become more apparent, a photosensitive member having less abnormal growth is required.
Because these defects, i.e. specifically abnormally grown portions is very small, it is difficult to detect the presence of them even when the conductivity is measured by setting an electrode at the top. However, when an electrophotographic photosensitive member is subjected to charging, exposure and development in accordance with the electrophotographic process, particularly to form an uniform picture in half tone, even a slight potential difference on the surface of the electrophotographic photosensitive member appears as a visually-remarkable image defect. Particularly, in the case of an electrophotographic photosensitive member formed by the microwave plasma CVD method, the above problem frequently appears.
In the case of an electrophotographic photosensitive member formed by the plasma CVD method, the above image defect especially appears compared to an Se electrophotographic photosensitive member manufactured by vacuum deposition or an OPC electrophotographic photosensitive member manufactured by the blade coating method or dipping method.
Moreover, even in the case of a device like a solar cell manufactured by the same plasma CVD method, a delicate characteristic difference due to the position of a substrate does not influence its performance. Furthermore, in the case of a device that can be repaired by post-treatment, the above trouble does not occur.
Furthermore, the step of cleaning a substrate with triethane has no problem in the prior art. However, the step has been changed to the water-based cleaning step due to recent environmental problems and thereby because chlorine-based solvents cannot be easily used. However, when cleaning aluminum with water, a portion containing many impurities (e.g., Si) and locally exposed to the surface of the aluminum forms a local battery with peripheral normal aluminum to accelerate uncontrolled corrosion on the surface of a substrate.